空气节流对超燃发动机燃烧性能的影响
Air-throttling effect of scramjet combustion characteristics
-
摘要: 为优化隔离段及燃烧室内的流场结构,减小流动速度,提高流道压力,在凹槽稳焰器下游布置空气节流装置,向燃烧室内喷入高压空气,目的是在隔离段建立合适的激波串,以利于点火和火焰稳定.采用CFD方法,对比了无/有空气节流时的冷流流场、燃烧流场,结果表明:节流激波串扩大了低动量区域,激波引起的流动扭曲和较长的驻留时间使得分离流内的空气/燃料混合程度得到显著增强,混合效率由无节流时的40%提高到85%,燃烧效率由无节流时的10%提高到60%.对节流位置和节流量进行了参数化研究,以隔离段入口为坐标原点,分别考察了785,1000,1100mm三个流向节流位置,以及10%,15%,30%三种节流量的影响,结果表明:距离凹槽较近的节流位置对燃烧的影响更为显著,所需节流量更少.30%的节流量将使燃烧室背压急剧提高,引起流动壅塞.研究表明在785mm的流向节流位置采用15%的节流量可获得最好的燃烧性能.Abstract: Compressed air was introduced into the combustor to establish pre-combustion shock train.The main purpose of air throttling is to optimize flow structure of isolator and combustor to reduce the local flow velocity,increase the pressure and make ignition and combustion easier.Using CFD method,the cold and reactive flow fields with/without air throttling were compared.The results show that the throttling shock enlarges low momentum regions and slows down the air/fuel mixture.The flow distortion caused by the throttling shock and extended residence time enhance air/fuel mixing remarkably.The mixing efficiency increases from 40% to 85%.Also the combustion efficiency increases from 10% to 60%.A parametric research was conducted to investigate the effect of throttling location and throttling mass flow rate on the combustion characteristics.Three throttling locations,x=785mm,x=1000mm and x=1100mm,and three throttling mass flow rates with 10%,15%,30% were studied respectively.The results show that the effect of the nearest throttling location is most notable,where the least throttling mass is required.30% throttling mass flow rate increases back pressure sharply and makes the flow choked.In the given condition,throttling with 15% air flow mass at x=785 mm obtains the best combustion efficiency.
-
Key words:
- scramjet /
- air-throttling /
- mixing efficiency /
- combustion efficiency /
- throttling mass /
- throttling location
-
[1] 刘欧子.双模态冲压发动机燃烧室碳氢燃料凹槽火焰稳定性研究[D].西安:西北工业大学,2006. LIU Ouzi.The characteristics of the cavity flame holdersinthe dua-mode seramjet combustor with hydrocarbon fuel[D].Xi'an:Northwestem Polytechnical University,2006.(in Chinese) [2] Li J,Ma F H,Yang V,et al.Control and optimization of ignition transient in scramjet engine using air throttling[R].AIAA 2006-1028,2006. [3] Hsu K Y,Carter C,Gruber C J,et al.Fuel distribution about a cavity flameholder in supersonic flow[R].AIAA-2000-3585,2000. [4] Kanda T,Tani K.Momentum balance model of flow field with pseudo-shock[R].AIAA 2005-1045,2005. [5] Tomioka S,Izumikawa M,Akuranaka N,et al.Mixing control by wall flush-mount injectors in dual-mode combustor[R].AIAA 2010-6959,2010. [6] Kobayashi T,Matsuo A,Tomioka S,et al.Numerical study on airflow/jet mixing enhancement by pseudo-shock wave system[R].AIAA 2010-6961,2010. [7] Mathur T,Lin K C,Kennedy P,et al.Liquid JP-7 combustion in a scramjet combustor[R].AIAA-2000-3581,2000. [8] Donbar J,Powell O,Gruber M,et al.Post-test analysis of flush-wall fuel injection experiments in a scramjet combustor[R].AIAA 2001-3197,2001. [9] Gruber M,Donbar J,Jackson K,et al.Newly developed direct-connect high-enthalpy supersonic combustion research facility[J].Journal of Propulsion and Power,2001,17(6):1296-1304. [10] Yang V,Li J,Choi J Y,et al.Ignition transient in an ethylene fueled scramjet engine with air throttling:Part Ⅰ non-reacting flow development and mixing[R].AIAA 2010-409,2010. [11] Yang V,Li J,Choi J Y,et al.Ignition transient in an ethylene fueled scramjet engine with air throttling:Part Ⅱ ignition and flame development[R].AIAA 2010-410,2010. [12] 刘林峰,徐胜利,郑日恒,等.超声速气流中凹槽结构煤油喷射和掺混研究[J].推进技术,2010,31(6):721-729. LIU Linfeng,XU Shengli,ZHENG Riheng,et al.Studies on kerosene injection and mixing with cavity in supersonic flow[J].Journal of Propulsion Technology,2010,31(6):721-729.(in Chinese) [13] 李大鹏.煤油双模态冲压发动机燃烧室工作过程研究[R].长沙:国防科学技术大学,2006. LI Dapeng.Study of kerosene fueled dual-mode ramjet combustor operation process[D].Changsha:National University of Defense Technology,2006.(in Chinese) [14] 杨顺华.碳氢燃料超燃冲压发动机数值研究[D].绵阳:中国空气动力研究与发展中心,2006. YANG Shunhua.Numerical study of hydrocarbon fueld Scramjet[D].Mianyang:China Aerodynamics Research and Development Center,2006.(in Chinese) [15] Imlay S T,Roberts D W,Soetrisno M,et al.Nonequilibrium thermo-chemical calculations using a diagnonal implicit scheme[R].AIAA-91-0468,1991.
点击查看大图
计量
- 文章访问数: 1758
- HTML浏览量: 4
- PDF量: 1342
- 被引次数: 0